A freshly leaked internal Apple document has surfaced online detailing the Service Eligibility Guidelines for iPhone 6, iPhone 6s and iPhone 7 series of handsets.

In other words, the 22-page document reveals how the company decides whether to offer an in-warranty or out-of-warranty service, or deny the service altogether.

The document is better known as VMI or 'Visual/Mechanical Inspection Guide', which will be used by Apple's technicians and authorised service personnel to understand what kind of service any customer will be eligible, based on the nature and cause of damage to the device.

"We have one just like that for all of the products," one Apple retail technician told Business Insider.

"Used more for the physical inspection and how to determine cost for damage. That's basically half the training for iPhone techs," he explained.

Any pixel anomaly with the affected device's display, dirt, small hairline crack on the cover glass of display, and a misalignment of the FaceTime camera are supported under in-warranty repair. Furthermore, all those devices which are affected with any one of these issues will be repaired for free under warranty, even if there is another accidental or liquid damage to the device.

Whenever in-warranty service is not possible for such exceptional cases, Apple recommends replacing the faulty unit to the customer regardless of any accidental damage.

Apple Technicians need to make up the decision whether to offer an in-warranty service to affected devices, especially if they are completely broken due to accidental or liquid damage while there is no sign of any manufacturing defect in the unit.

According to VMI's rule of thumb, no service should be offered for accidental or liquid damage claims if the unit is tampered or mishandled by the user or third-party technician. In all such cases, Apple technicians can simply deny the service.

The rules in the VMI are meant to help technicians only under special circumstances and not as a blind instruction.